1. Field of the Invention
The preset invention relates to disk drives. More particularly, the present invention relates to a disk drive head disk assembly that includes a ramp having pivoting locational features.
2. Description of the Prior Art
Ramp-loading disk drives utilize a ramp to transition a flying head off-of and back-onto a flying area above the surface of the rotating media. The ramp typically interacts with a feature of the gimbal assembly that supports the flying head. The media is spun-up while the gimbal assembly is supported by the ramp and the head is not in contact with the media. Once the media is rotating at a specified speed, the gimbal assembly and head are moved down the ramp such that an air bearing is developed head and the media. The gimbal assembly and head then move free of the ramp. Before the media is spun-down, the gimbal assembly is moved onto the ramp such that the head is moved away from the media.
The design of lower flying heads, tighter disk spacing in the disk stack and increased reliability requirements have lead to ramp designs that overhang the media in the radial direction. An overhanging ramp design, however, causes complications in the assembly of the drive. After disk (media) stack installation, the ramp cannot be loaded onto the disk drive baseplate with a simple vertical motion, which is the preferred high volume manufacturing method. Further, to minimize the disks"" exposure to potential handling damage, it may be preferable to assemble the disk stack onto a spindle motor/baseplate assembly that already supports the head stack assembly and the Voice Coil Motor (VCM). In turn, this assembly sequence dictates that the overhanging ramp must be retracted (while still supporting the heads) during assembly to allow disk install. To prevent damage to the read/write heads during the retraction of the ramp, the retraction motion must be controlled in a repeatable and smooth manner. Additionally, for rework assembly, it is preferable to remove a disk or the disk stack without removing the head stack and VCM; or conversely, to remove the head stack and VCM without removal of the disk stack.
Existing ramps require both a vertical and horizontal motion during assembly. This design constrains the assembly sequence, such that the disk stack must be installed first, followed by installation of the ramp and the head stack, which must be installed last. Conventionally, if a disk must be replaced, both the head stack and the ramp must be removed first. Competitive pressures, however, have led the disk drive industry to strive to find ways to lower the cost of assembling disk drives. The structure of the head disk assembly has been targeted as a candidate for such cost cutting measures. What is needed, therefore, is a head disk assembly that eases the above-detailed constraints placed upon the disk drive assembly and rework processes. Such a head disk assembly should lower assembly and rework costs by not requiring both vertical and horizontal motions during assembly and/or rework and by allowing removal of the disk stack without first removing the ramp or the head stack.
Accordingly, this invention may be regarded as a head disk assembly, including a disk, a head stack assembly and a ramp-defining structure. The disk has a recording surface surrounded by an outer circumference and the head stack assembly has an actuator pivot axis and a head gimbal assembly. The head gimbal assembly includes a gimbal defining a gimbal axis parallel to and spaced a first distance from the actuator pivot axis, and a lift tab having a lift-surface portion spaced a second, larger distance from the actuator pivot axis. The ramp-defining structure includes a wall extending parallel to the actuator pivot axis, an axis-defining portion defining a retraction pivot axis and a shelf projecting from the wall to define a bearing surface against which the lift-surface portion slides during unloading and loading operations. The bearing surface has a meandering and undulating shape to define a retention portion and a cam portion. The retention portion defines an arc relative to the retraction pivot axis, and the cam portion defines an arc relative to the actuator pivot axis. The ramp-defining structure also includes means for releasably securing the ramp-defining structure relative to the disk such that in a secured condition the cam portion overlies the outer circumference and in an unsecured condition the cam portion can be moved to a position clear of the disk while the lift-surface portion slides on the retention portion.
According to further embodiments, a first end of the axis-defining portion may define a pair of facing keyed notches that forms a keyed gripping feature allowing a tool to grip and rotate the ramp-defining structure about the retraction pivot axis when the securing means is in the unsecured position. A second end of the axis-defining portion may define a chamfered lead in that facilitates accurate positioning of the ramp-defining structure relative to the lift-surface portion as the ramp-defining structure is assembled onto a disk drive baseplate. The ramp-defining structure may include a surface defining a through bore configured to receive the securing means, the through bore being aligned with a corresponding threaded bore in a disk drive baseplate when the ramp-defining structure is in an operational position in which the cam portion overlies the outer circumference.
The present invention may also be viewed as a head disk assembly, including a disk, a head gimbal assembly, a ramp-defining shelf and releasable securing means. The disk has a recording surface surrounded by an outer circumference. The head gimbal assembly is supported to swing relative to an actuator pivot axis and includes a gimbal defining a gimbal axis parallel to and spaced a first distance from the actuator pivot axis, and a lift tab having a lift-surface portion spaced a second, larger distance from the actuator pivot axis. The ramp-defining shelf is supported to swing relative to a retraction pivot axis, the shelf including a retention portion and a cam portion, the retention portion defining an arc relative to the retraction pivot axis, and the cam portion defining an arc relative to the actuator pivot axis. The releasable securing means secures the ramp-defining shelf relative to the disk such that in a secured condition the cam portion overlies the outer circumference and in an unsecured condition the cam portion can be moved to a position clear of the disk while the lift-surface portion slides on the retention portion.
The foregoing and other features of the invention are described in detail below and set forth in the appended claims.